1^8 SECRETORY RESERVOIRS. 



according to Holzner, to the klinorhombic systejn. Besides these different, singly 

 developed crystals, there often occur others imperfectly developed, and grown 

 together to angular or stellate groups, which, according to Holzner, may belong as 

 well to one system as to the other. The form and system of crystallisation is 

 indefinite in the case of the quite small crystals, which often occur, and appear more 

 like small granules : on these sharp angles and edges may be recognised with a high 

 power. 



In the sacs the fully developed klinorhombic forms and the groups almost 

 always occur singly, rarely two together, and fill the greater part of the cell : the 

 Raphides appear always in larger number ; as a rule they are nearly equally long and 

 parallel and are closely packed in the sac in a bundle, so that all the ends in the 

 same direction are in one plane ; more rarely they vary in length and direction, as in 

 the cortex of many species of Aloe, e.g. Aloe arborescens, in the parenchyma of 

 Mirabilis, and the very small Raphides in -the numerous crystal- sacs of the Cinnamon- 

 bark of Ceylon. Here the minute granule-like crystals in an innumerable multitude 

 fill the sac completely, so that in transmitted light it appears to have quite black, 

 densely granular contents : the same occurs in the herbaceous parts of many Solanese', 

 of Amarantus retroflexus, caudatus, and allies, Sedumi ternatum, in the pith and 

 cortex of Sambucus nigra, the cortex of Betula verrucosa, Alnus glutinosa, Staphylea 

 pinnata ^, and the bark of the officinal species of Cinchona '. 



The form of the crystal-bearing sacs is closely related to that of the crystals 

 contained in them, when the latter attain considerable size ; but it cannot at present 

 be definitely stated whether the form of the crystal is dependent upon that of the 

 sac, or the converse. The iso-diametric grouped crystals are contained in sacs re- 

 sembling them in shape, the shorter or longer klinorhombic forms fill sacs of cor- 

 responding shape, which are even of very much elongated prismatic or spindle form, 

 e.g. in the rhizome and leaf of species of Iris*, and in the leaf of Aloe Africana. The 

 sacs containing raphides are elongated in the same direction as the bundle of 

 raphides where the raphides are very large, as in the cortex of Aloe arborescens, in 

 the bulb of Scilla maiitima they often attain a great length, in the latter case more 

 than 5mm 5 



These phenomena appear very striking in the bast-bundles of dicotyledonous 

 plants, the tissue-elements of which are derived from elongated spindle-shaped cam- 

 bial cells. The crystal-bearing sacs arise in this case by transverse division of a 

 cambial cell (Chap. XIV) ; in those of Guajacum, and Quillaja, which contain a single 

 elongated klinorhombic crystal, few divisions occur : each of the products of this pro- 

 cess (? all of them) becomes one crystal-bearing sac. Also it often happens in plants 

 with small solitary crystals or groups of crystals, that only single products of trans- 

 verse division may develope to crystal-bearing structures, fiut in very many ligneous 

 plants one cambial cell divides by transverse walls into numerous chambers (zo-30), 

 which are hardly or not at all higher than broad, and each of these is filled by a 

 crystal or a group. The general outline of the original cambial cell is meanwhile 



^ Corda, Beitr. z. Kunde d. Kaitoffel, &c., in Hlubeck's CEcon. Neuigkeiten, 1847, Nos. 58-60. 

 ^ Sanio, Monatsbr. d. Berliner Academic, April, 1857. 



' Fliickiger, Pharmacognosie, p. 365. * Unger, Anat. imd Physiol, p. 123. 



' Fliickiger, Pharmacognosie, p. 187. 



